Optics: when are images virtual and when are they real?

In summary, the difference between a real and virtual image is that a real image exists in the physical world and can be captured on a screen, while a virtual image only exists in the mind of the observer and is created through the interpretation of divergent rays of light. Real images are formed by converging rays of light, while virtual images are formed by diverging rays. This distinction is important in understanding how images are created and perceived.
  • #1
Joe626
14
0
sorry, no specific homework question, although it is related to my homework in general. I don't understand what makes an image real or virtual.

thanks for the help :)

joe
 
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  • #2
See this video for a virtual image:

http://www.khanacademy.org/video/virtual-image?playlist=Physics

The real images really exist. The virtual image exist in the brain of the observer.

More seriously: In case of real image, the rays emerging from a point of an object become convergent after passing the imaging system (mirror or lens) and intersect in the same point: at the image of the object.
In case of virtual image the rays emerging from a point of the object are divergent after leaving the lens or mirror. The divergent rays arrive to the eye and the brain interprets them as coming from a common point - from the image. But this common point does not exist in reality.

ehild
 

1. What is the difference between virtual and real images in optics?

Virtual images are formed by light rays that appear to come from a certain point behind the mirror or lens, while real images are formed when light rays physically converge at a point in front of the mirror or lens. Real images can be projected onto a screen, while virtual images cannot.

2. How can I determine if an image formed by a mirror or lens is virtual or real?

To determine if an image is virtual or real, you can use a simple test known as the "finger test." Place your finger in front of the mirror or lens between the object and the mirror/lens. If the image of your finger appears to be behind the mirror/lens, the image is virtual. If the image of your finger appears to be in front of the mirror/lens, the image is real.

3. Are virtual images always upright and real images always inverted?

No, this is not always the case. The orientation of an image depends on the position of the object and the type of mirror or lens used. For example, a concave mirror can produce both virtual and real images that are either upright or inverted.

4. Can real images be formed by a diverging lens?

Yes, real images can be formed by a diverging lens. However, they are always smaller than the object and located on the same side of the lens as the object. This type of image is called a virtual image.

5. What is the significance of virtual and real images in practical applications?

Virtual and real images have various practical applications, such as in telescopes and microscopes. Real images are also used in photography and cinematography. Additionally, virtual images are used in rearview mirrors and in the design of periscopes and other optical instruments.

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